Mobile radio frequency band(s) are both scarce and precious resources. After the inception of commercial mobile radio communication in the 1980's the numbers of subscribers have been growing exponentially. The underlying radio technology also has grown at a fast pace. In addition to conventional voice communication, data, video and real time gaming have been introduced.
These new services require a relatively higher number of bits transmitted in a unit time than conventional voice services. There are two main ways to achieve larger bit rate demands, first, efficient use of spectrum using advanced technology (based on, for example, multiple transmit and receive antennas) and, second, the use of a larger frequency band. As the frequency spectrum is already crowded the latter is often not feasible.
A service area may be divided into grids of macro cells, which may include clusters of smaller cells. The frequency band may be apportioned between the clusters so as to intelligently keep the co-channel interference low.
Small cell deployments within a larger macro cell efficiently use the spectrum and deliver the demand for the higher bit rate in the cell coverage areas. Generally the small cells use lower transmit power to serve a small area in the hot spot or hot zone where the demand for the service is high with high density of users, or in other words, they have a cell radius of a few meters to a few hundred meters. Small cells may use wireless or wired backhaul connections to the back bone network.
Wireless networks using the long-term evolution (LTE) standard may employ features, Coordinated Multi-Point Operation (CoMP), that allow UEs to be serviced by more than one base station. For example, when a UE works under the CA mode, the UE may be served by two or more cells, where one of the cells acts as a primary serving cell, and other cells act as secondary serving cells. Similarly, CoMP allows UEs to be served by more than one base station in order to enhance quality of service (QoS) on the perimeter of a serving cell.
Resource and spatial coordination are aspects in CoMP technologies in wireless communication to improve system capacity. Most of techniques in the CoMP technology developments use a centralized controller/scheduler for resource and spatial coordination among transmission points (TPs) in the CoMP cooperating set.